1. Field Of The Invention
The present invention concerns containers used for holding, and dispensing, photographic developing liquids, particularly heated fluid developer, within and to a machine that develops photographs, particularly microfilm.
2. Background Of The Invention
Various modern machines develop photographs in an automated, or semi-automated, process. The liquid chemicals used in the photographic development process, including fluid developer, are consumed during the machine process of photographic development. These consumable liquid chemicals must be (i) delivered fresh to the machine, (ii) circulated during the photographic development process within the machine, and (iii) extracted from the machine when spent. The delivery is normally periodic as required, in bottles.
One particular machine that uses photographic chemicals in an automated photographic development process is a computer output on microfilm (COM) machine that images, and develops, microfilm. Previous containers, and plumbing, for the delivery of liquid photographic chemicals to COM and other machines have characteristically been both cumbersome and problemsome.
In one particular COM machine made by the assignee of the present invention--which machine functions commensurately with many other machines using liquid photographic chemicals to develop photographs--liquid photographic chemicals are delivered to the machine in capped cylindrical plastic bottles. The caps of such bottles are removed, and a takeup tube by which the liquid chemicals are extracted from the bottle to the machine is inserted through the neck of the bottle. A return fluid path is also provided from the machine into the bottle so that excess liquid chemical recycled from photographic development process may be returned to the bottle. This path also typically proceeds through a tube--the return tube--that extends from the machine through the neck of the bottle into a space above the bottle's liquid reservoir. The liquid photographic chemical typically circulates in a continuous loop that includes a reservoir of chemical within the bottle.
Each liquid photographic chemical is normally filtered during the course of its circulation.
At least one liquid photographic chemical--fluid developer--is also normally heated during the course of its circulation. The heating of fluid developer is done so that it may be raised to, and maintained at, an optimum temperature for use in the photographic development process.
The heating is typically accomplished by electrically resistive heating elements located in-line the fluid flow path. The fluid developer, which is mildly corrosive, must not be allowed to cause shorts in the resistive heating elements. Accordingly, the heating elements are normally required to be made from a non-corroding metal in order to improve their service life and reliability. Problems with such heating elements include that they are typically expensive, hard to clean, and subject to clogging.
Another problem is oxidation of the fluid developer. It is well known that fluid developer is prone to oxidation from contact with air. The oxidation impairs the chemical suitability of the developer. Ordinarily the fluid developer is continuously circulated in order that it may be heated and ready for use during the development process. This continuous circulation agitates the fluid developer, exposing it to air and causing it to undergo oxidation at an increased rate.
Still another problem with previous bottle is that they have proven cumbersome and hazardous during interchange. When the takeup and return tubes are withdrawn from the neck of a spent bottle they typically drip copious amounts of liquid chemical. The dripped chemical tends to get on the external surface of the bottle, and from there onto the hands and clothing of a human. The chemical may also accumulate on the floor of the machine. Fluid developer, in particular, is a skin irritant that stains clothing. Interchange of bottles has not only proved to be a messy operation, but hazardous as well, with possible contamination of the environment.
Yet another problem arises when a filter within a fluid circulation line must be changed. The fluid takeup and return tubes are typically detached from the machine in order to permit access to the filter. The filter, which is itself saturated with fluid, must then be manually extracted from the machine and either cleaned or replaced. This preventive maintenance task of extracting, and changing or cleaning the filter is not only difficult and messy, but may as well contaminate the environment and/or persons. Because of the difficulty and messiness of the task it is often performed more infrequently than is desireable for maintaining the machine and its fluids in satisfactory operating condition.
Accordingly an improved container/delivery system is needed which would: (i) permit heating of circulating fluid developer without the use of expensive non-corroding heating elements, (ii) reduce the oxidation of fluid developer occurring from and during its continuous circulation, (iii) reduce or eliminate personal and environmental contamination from spilled fluids, (iv) improve the ease and reliability of connecting containers of liquid chemical to a machine, and (v) improve preventive maintenance by promoting the cleaning or substitution of fluid filters.